The tibial muscles of the Ostrich

Abstract

The tibial muscles of an adult male ostrich which died at Ueno Zoo, Tokyo, 1959, was examined. Unfortunately, only the muscles of the right leg was available and they were already cut at the heel joint, and the time was not enough for detail examination. Of the 13 tibial muscles to be found in oridinal birds, nine (if M. perforatus et perforans digiti II and III (Fig. 1, E) are separated, ten) were present and are briefly described. The total muscle weight was 5.950gm, M. gastrocnemius and M. peroneus longus, especially the former, were extremely developed completely enveloping the hole proximal part of the tibia. Other muscles, mostly with tendon to toes and also M. tibialis anterior which lifts the tarsus, were only weakly developed. These conditions are adaptations for the use of heavy tarsus solely for running. But, the general muscular system, though simplified, was similar to that of ordinal avian type.